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If the conductor 'CD' rotates in clockwise direction in the figure, voltage will be induced on it. What will be the polarity of the voltage on terminal of the conductor 'CD' when the conductor rotates in clockwise direction according to the right hand rule.

If the conductor CD rotates in counterclockwise direction what will be the polarity of the conductor 'CD' on its terminnal? Will it be same like when the conductor was moving in clockwise direction or will be opposite that that according to the Fleming's right hand rule?

enter image description here ?

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  • \$\begingroup\$ Since this looks like homework you need to show what you have worked out yourself. Edit your post and add it in. \$\endgroup\$
    – Transistor
    Commented Mar 8, 2018 at 10:52
  • \$\begingroup\$ This is a duplicate of your previous question: electronics.stackexchange.com/questions/359328/… \$\endgroup\$
    – MrGerber
    Commented Mar 8, 2018 at 11:43

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Just consider a single conductor connected to an ammeter: -

enter image description here

Picture source

So, if the conductor is moving upwards (as shown), Fleming's right hand rule tells us that current will flow into the page (as shown): -

enter image description here

Align your hand so that your index finger is pointing left to right to correspond with the field line directions of north to south in the top picture.

Now, if the force was downwards you would have to rotate your hand through 180 degrees to keep the field in the same direction but now your thumb (movement) would be pointing down. This means your middle finger (current) is pointing outwards from the page.

So that's the currents but what drives that current? An induced voltage drives the current and that has a polarity that must reverse direction to drive current in the opposite direction.

If the conductor CD rotates in counterclockwise direction what will be the polarity of the conductor 'CD' on its terminnal?

If CD is moving down through the magnetic field and is beginning this process at the top (as shown in the OP's diagram), then a voltage is induced that pushes current in the direction D to C (note that N and S are in opposite places on my diagram to the OP's).

Notice also that rotation direction is irrelevant because the same voltage (amplitude and polarity) will be produced when the wire moves downwards through the magnetic field irrespective of whether it takes a counter clockwise or clockwise route.

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  • \$\begingroup\$ so polarity and magnitude of the voltage on the conductor will be same whether it is rotated clockwise or counterclockwise as long as the movement is in downward direction ? @andyaka \$\endgroup\$
    – Alex
    Commented Mar 8, 2018 at 14:10
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    \$\begingroup\$ Correct... it is the direction that a wire cuts lines of flux that dictates polarity of induced voltage. \$\endgroup\$
    – Andy aka
    Commented Mar 8, 2018 at 14:15

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